R help - Aug 2007 - substituting elements in vector according to sample(unique(vector))

Hello!

Assuming I have a vector, such as

v <- c(1,2,1,2,3,3,1)

This vector has three unique elements: 1, 2, and 3.
> unique(v)
[1] 1 2 3

If I shuffle this vector of unique elements, I get something like this:
> sample(unique(v))
[1] 3 2 1

In the vector v I started with, I would now like to replace each element in
unique(v) with the corresponding element (i.e. the element with the same
index) in sample(unique(v)).

In this case, the result should be something like c(3,2,3,2,1,1,3).

In particular, I would like to do this without a slow for loop.
I have tried things like sub(), but they don't seem to be appropriate.
Can anyone provide an elegant solution?

Thank you,

Arthur Wuster
Theoretical and Computational Biology
MRC Laboratory of Molecular Biology
Cambridge, UK

try the following:

v <- c(1, 2, 1, 2, 3, 3, 1)
x <- c(3, 2, 1)

fv <- factor(v, levels = x)
as.vector(unclass(fv))


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Arthur Wuster" <awuster at mrc-lmb.cam.ac.uk>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, August 28, 2007 4:12 PM
Subject: [R] substituting elements in vector according 
tosample(unique(vector))

>
> Hello!
>
> Assuming I have a vector, such as
>
> v <- c(1,2,1,2,3,3,1)
>
> This vector has three unique elements: 1, 2, and 3.
>
>> unique(v)
> [1] 1 2 3
>
> If I shuffle this vector of unique elements, I get something like 
> this:
>
>> sample(unique(v))
> [1] 3 2 1
>
> In the vector v I started with, I would now like to replace each 
> element in
> unique(v) with the corresponding element (i.e. the element with the 
> same
> index) in sample(unique(v)).
>
> In this case, the result should be something like c(3,2,3,2,1,1,3).
>
> In particular, I would like to do this without a slow for loop.
> I have tried things like sub(), but they don't seem to be 
> appropriate.
> Can anyone provide an elegant solution?
>
> Thank you,
>
> Arthur Wuster
> Theoretical and Computational Biology
> MRC Laboratory of Molecular Biology
> Cambridge, UK
>
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> R-help at stat.math.ethz.ch mailing list
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> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

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